When a computer system is subjected to a shock force, such as striking the floor after a fall from a desktop, a hard disk drive (HDD) of the computer system is less likely to be damaged if the head is parked. An accelerometer, either a two-dimensional (2D) or three-dimensional (3D) version, may be used for identifying the start of a freefall. However, in order to maximize the chances that the HDD head is parked before the computer strikes the floor, the freefall event should be communicated with minimal delay.
Computer systems use devices which may comply with a number of different industry standard specifications such as Peripheral Component Interconnect (PCI) and/or PCI Express, which are the current favored standards for plug-in cards, and Industry Standard Architecture (ISA), which is an older generation standard for plug-in cards. Interrupt requests (IRQs) are often used by PCI-compliant devices for low latency event communication by directly signaling a central processing unit (CPU) of the computing system. Unfortunately, some cost-effective accelerometers that could be used to detect a freefall are non-PCI devices (i.e., a device which does not conform to the industry standard PCI specification). One example of such a non-PCI accelerometer is an inter-integrated circuit (I2C) bus device. Unfortunately, I2C bus devices lack the ability to use an IRQ and, therefore, do not have the same native capability for low latency event communication as do PCI devices. Accordingly, latency associated with typical I2C bus messaging methods result in an increased likelihood of damage to the HDD if a freefall event is detected if a non-PCI device is used to detect the freefall event.